System Tweaking Guide - VCache - By Mark "Frugal" Bush
VCache is a read
ahead file cache designed to speed up Windows file handling. Because
Windows will by default assign all available ram to be used as
a potential cache it is very important to tweak it. Many people
say that there is no need to tweak VCACHE on Win98 or ME but this
simply isn't true. Here is Microsofts description of VCACHE
"The Windows 32-bit protected-mode cache driver (Vcache)
determines the maximum cache size based on the amount of RAM that
is present when Windows starts. Vcache then reserves enough memory
addresses to permit it to access a cache of the maximum size so
that it can increase the cache to that size if needed. These addresses
are allocated in a range of virtual addresses from 0xC0000000
through 0xFFFFFFFF (3 to 4 gigabytes) known as the system arena."
This can cause big problems if you have a large amount of Ram
ie more than 512MB. Microsoft offer the following description
of the the problem: "On computers with large amounts of RAM,
the maximum cache size can be large enough that Vcache consumes
all of the addresses in the system arena, leaving no virtual memory
addresses available for other functions such as opening an MS-DOS
prompt (creating a new virtual machine). "
Vcache can and should be tweaked in order to improve the performance
and avoid the afforementioned problems. A lot of the stuttering
that people get in Falcon 4 and other sims is caused indirectly
by this caching process. VCache uses the ram forcing Windows to
use the Swap file. As Windows writes to the hard drive, the game
pauses. By setting a minfilecache and maxfilecache you can control
the process .What you are aiming for when tweaking VCACHE is to
allow enough memory to be used for the cache to improve performance
while ensuring that the cache dosen't eat up all your ram forcing
the swap file to be used.
How you tweak VCache is really dependant on the amount of ram
you have. Generally there is no need for a minimum setting as
there are no real gains to be had here. The maximum on the other
hand needs to be controlled in order to get the best performance.
As a basic rule, a large maxfilecache will speed up the file system
but will cause the swap file to be used more. Ideally you want
to achieve fast file access and minimum swap file usage. Unfortunately
there are no hard and fast rules for the exact setting to use.
I have experimented to find some good general settings which you
will find below. You may want to tweak these further by using
the system moniter tracking Swap File In Use and Disk Cache Size.
The VCache settings are in the system.ini on Windows 95 or 98
the easiest way to edit them is to click Start select Run then
type "sysedit" without the quotes into the box then
hit ok. On Windows ME you will need to got to Start | Run then
type in msconfig. This will bring up the system configuration
editor. From there you can edit your system.ini. You will find
a section headed [VCACHE] if it is not there you can add it yourself.
The following are the settings I would reccomend based on the
amount of ram you have.
Before editing your system.ini be sure to make a back up as todging
your system.ini by deleting something you shouldn't etc is very
bad and Windows won't like it!!
384 MB or above
[VCACHE]
MaxFileCache=61440
256 MB
[VCACHE]
MaxFileCache=30720
192 MB
[VCACHE]
MaxFileCache=24576
128 MB
[VCACHE]
MaxFileCache=16384
64 MB
[VCACHE]
MaxFileCache=8192
32 MB or below:
I Know this is gonna sound harsh but I reccomend you buy more
ram. 32 MB is way below entry level and more games are becoming
memory intensive. Ram is dirt cheap these days. You can pick up
128 MB of SDRAM for £20. Or a similar amount of US dollars.
UPDATE: I received an email from Horseman confirming that the
tweaks on this page work. He also included the following information
for people limited to 32mb:
"The best frame \ lack of delay performance I have attained is
at the vcache min\max setting 2048/2048. This is at a very acceptable
level. That level attained with resource meter open, reducing
user and sys resources to 81% and gdi resources to 90% available.
Then closed resource meter."
"I am still testing different game graphics settings. I
will report these settings to you if you like. Hopefully this
info may benefit others in the same pc boat as i am in to enjoy
the sim as best as possible.
My graphics levels are definately not twin voodoo class but
are much much better than original install speed without the
partition,swp file move, and vcache tweaking. Thanks for the
great tech advice!"
Well thanks for that Horseman if anyone else makes any discoveries
or knows of any neat tricks that can boost performance by all
means mail me.
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